HaikuDepot: Keep aspect ratio of Bitmap in BitmapView
HaikuDepot: Add screenshots from resources to dummy package infos.
HaikuDepot: Display the first screenhot in the package contents area.

 * Disabled BitmapView::GetHeightForWidth() to keep aspect, it seems
   broken in the layout system, the view gets layouted completely
   elsewhere. Mabye due to the layout hierarchy being optimized?
 * Instead layout the bitmap with correct aspect in the given space,
   honor LayoutAlignment() for this.